Expand Arrow Duplicating

Hi,

I haven’t spotted a thread with a similar problem. For some reason, when I click the trigger text to expand an article, the arrow changes to the collapse arrow but duplicates itself, with one appearing below the other. When I click to collapse, the arrows change back to the expand arrows but remain duplicated.

Here’s the page: http://fort.jeffreydriver.co.uk/the-team/

I’ve tried it in different browsers and had the same result. WordPress and plugins are all up to date.

https://wordpress.org/plugins/jquery-collapse-o-matic/